Updated Google's Chrome browser has added a Do Not Track option that will prevent websites using your browser history to target ads at you.*

Pioneered by Mozilla Firefox, the Do Not Track convention adds a field in the HTTP header of each web page instructing websites not to take info about you from your browser. Commonly used to prevent overly personal targeted ads, Do Not Track also stops web visitors having their data picked through by websites' social features and analytics engines. Microsoft claims that Internet Explorer doesn't track its users and Do not Track is an option in Safari.

The Chrome extension that allows you to opt out of tracking – Keep My Opt Outs – is now live in Google's apps store.

It's not a movement that Google has been overly eager to embrace, considering that it is the one making the most cash out of targeted ads, and considering that targeted ads are more valuable than generic ones. However the web giant's hand has been forced as the Do Not Track movement gathers momentum, as evidenced by the Californian ruling on tracking mobile internet users yesterday.

In a last-ditch attempt to protect Google's revenue, its the Do Not Track extension comes with the plaintive suggestion that you don't install it.

Websites, ranging from small sites operated by individuals to large sites operated by corporations, offer you free content and services because they are supported by advertising. Blocking ads eliminates the primary revenue source for most web publishers. We want to give users control over their privacy while surfing the web, not force small web businesses to shut down.

* Update

Google has not yet added a Do Not Track option into Chrome, but instead is now making the third-party Keep My Opt Outs Chrome extension available in its Chrome Web Store.

A Do Not Track option is on its way, though, as a Google spokeswoman told The Reg in an email. "We're committing to two main changes," she wrote. "First, we'll build a Do Not Track option into Chrome. And second, our advertising systems will honor Do Not Track browser signals in accordance with DAA principles. We plan to implement these changes by the end of the year."

Once a user turns on the Do Not Track header, she told us, Chrome will transmit that directive to sites to which the user navigates. Websites and advertisers will see the header in the user's web request, and treat the user's browsing data in accordance with those DAA principles, including opting the user out of ad targeting and ads using third-party cookies. ®